1. Field of the Invention
The present invention relates generally to a buoyant cable antenna (BCA) suitable for submarine communications and, more particularly, to a reconfigurable buoyant cable antenna element for the (BCA) system.
2. Description of the Prior Art
The buoyant cable antenna is one of a host of antennas currently in use by submarines. It is used for wireless electronic communications while the submarine is submerged.
The prior art antenna element for a buoyant cable antenna comprises a core that consists of a cylindrical insulated single-wire with a cylindrical layer of insulation. A buoyancy layer/jacket is either injection molded or extruded in place onto the core to make the final structure a solid object. This arrangement makes it impossible to remove the core if the core becomes damaged or if a new kind of core is needed to meet a specific mission. This arrangement also makes it impossible to reconfigure the antenna for other applications or specific applications.
Current designs for buoyant cable antennas suffer from limited gain and bandwidth performance due to the resonant behavior of the antenna element. For example, it is not possible to insert circuit elements into the single-wire antenna to change its behavior due to the stress that is applied to the core during towing.
The following U.S. patents describe various prior art systems that may be related to the above and/or other buoyant cable antenna systems:
U.S. Pat. No. 5,745,436, issued Apr. 28, 1998, to Bittleston, discloses a semi-dry marine seismic streamer cable that consists of a number of connected streamer cable sections, which each comprise a mechanical jacket surrounding a hollow core enclosing seismic sensor and signal transfer means. Elongated axial stress elements for transmitting axial loads and a radial reinforcement member for relieving radial loads are provided in the jacket. The core is filled with a fluid or a fluid-saturated foam and the sensor means are mounted in the core by vibration isolating elements.
U.S. Pat. No. 6,426,464, issued Jul. 30, 2002, to Spellman et al, discloses a cable sectional assembly that houses an electrically concatenated series of electronic circuit modules and has electric hook-up media interspersed between the modules. Each run of interspersed hook-up media is surrounded by a flexible tubular member, which is oversized to allow movement of the hook-up media without restriction under flexing of the assembly. The assembly is a construction and arrangement of two forms of moldingly bonded encapsulations. The first of these forms is made of a hard encapsulant and forms a unitary encapsulation local to each electronic module which (i) encapsulates the circuit module and associated electrical coupling connections between the adjacent end of each individual run of an adjacent interspersed run of media and an electrical terminal of the module, and (ii) is securely bonded to the adjacent marginal end portions of the tubular members which surround the adjacent interspersed runs of hook-up media. The second form is an overmolded annular encapsulation made of a softer flexible encapsulant which fills the annular spaces between the encapsulations of the first form, and which is securely moldingly bonded to the midportion of the tubular member and the adjacent lateral surfaces of the encapsulations of the first form. Both the first and second forms of encapsulations are made of cool curing types of encapsulants.
U.S. Pat. No. 6,473,365, issued Oct. 29, 2002, to Joh et al, discloses a support structure of hydrophones for a towed array sonar system, which includes elastic members arranged in each sensor package and adapted to support a hydrophone received in the sensor package while attenuating vibrations transmitted to the sensor package. External vibrations, such as vibrations generated due to the running of a towing vessel or vibrations induced due to motions of a towing cable, which are irrespective of acoustic waves reflected by a target moving underwater, are attenuated by the hydrophone support structure during the transmission thereof from the sensor package to the hydrophones, so that the hydrophones are suppressed from vibrating due to the external vibrations.
U.S. Pat. No. 6,982,383, issued Jan. 3, 2006, to Spellman et al, discloses a cable section assembly for marine applications having a core structure, such as a buoyant cable antenna interim manufacturing step subassembly, and a protective casing formed from heat shrinkable tubing, which together with the interim subassembly forms a complete assembly. For buoyant cable assembly applications the interim subassembly is at least partially formed of polyurethane material having glass microballoons distributed therein, with such material in any event occupying an outer layer portion of the subassembly. The cable section assembly of the present invention is formed by providing a length of heat shrinkable flexible tubing, inflating or expanding the heat shrinkable tubing to its approximate full diameter, inserting the core structure into the length of tubing, and shrinking the tubing around the core structure.
U.S. Pat. No. 7,429,957, issued Sep. 30, 2008, to Tonn, discloses a buoyant cable antenna element that employs a specific double-negative meta-material sheath with a negative permeability. The double-negative meta-material sheath is disposed over the insulated wire portion of the buoyant cable antenna element. The double-negative meta-material sheath enables a deliberate reduction in the antenna wire inductance to a zero value at a desired critical frequency. Reducing the antenna wire inductance to zero creates a traveling wave structure antenna having enhanced bandwidth.
The above cited prior art does not disclose reuse of the core of the antenna element of a buoyant cable antenna and/or provide a core that can be removed and/or replaced by a different core and/or a core which may be customized for a particular application. Moreover, the above-cited art does not disclose an antenna element core that floats within air in a liner and/or which is slidable within the liner to be isolated from strain. Moreover, the above-cited art does not disclose an antenna element core for a buoyant cable antenna that permits the use of miniaturized electrical components in the antenna element itself due to the strain exerted during towing.
The solutions to the above described and/or related problems have been long sought without success. Consequently, those skilled in the art will appreciate the present invention that addresses the above and other problems.